Seismic Retrofitting of RC Frames: A Rational Strategy Based on Genetic Algorithms

This paper outlines a rational strategy for retrofitting Reinforced Concrete (RC), which is based on combing member- and structure-level techniques in order to achieve optimal design objectives in a Performance-Based approach. Member-level techniques (such as confinement with composite materials, steel or concrete jacketing) are supposed to enhance capacity of single members, whereas structure-level techniques (generally based on introducing steel bracings systems or shear walls) aim to reduce the seismic demand on the existing frame as a whole. A novel procedure, based on a “dedicated” genetic algorithms, is developed by the authors for selecting “optimal” retrofitting solutions, among the technically feasible ones, obtained by combining alternative configurations of steel bracing systems and FRP-confinement of critical members. The main assumptions about the representations of “individuals” and the main information about the genetic operations (i.e. selection, crossover and mutation) are summarised in the paper. Finally, a sample application of the procedure is proposed with the aim to demonstrate its potential in selecting rational retrofitting solutions.